1. Field of the Invention
The present invention relates to an apparatus and method of transceiving a service list which a wireless network provides to at least one terminal located in a wireless network coverage area. More particularly, the present invention relates to an apparatus and method of transmitting, in a data link, a service list without Internet protocol (IP) address allocation.
2. Description of Related Art
Currently, various services such as simple voice communication, image communication, data communication, instant messaging, movie viewing, web services, games, and the like, are portably used due to remarkable development of wireless networks. In particular, the development of wireless networks enables the services to be used at a low price.
However, it is required that a mobile communication terminal should first be connected to a mobile communication network, so that the mobile communication terminal may use the services, and a service type which the mobile communication network provides should also be checked. Since a service discovery module existing at the same layer or at a higher layer than a network layer should directly control message transmission, for checking a service list during the above-described process, a procedure in which an Internet protocol (IP) address is allocated in the network layer is required for service discovery.
An IP address allocation procedure for receiving a service list is problematic in that unnecessary traffic in a network is generated and the power of a terminal is consumed.
Also, a Link Layer Discovery Protocol (LLDP), approved as a standard in Institute of Electrical and Electronics Engineers (IEEE) 802.1AB, is a simple protocol for periodically informing to each device a case where a device such as a new router, a terminal, and the like, are installed in a wireless network, and where a network type is changed or a resource is changed.
Since the LLDP is operated in a link layer, compared with a case where a protocol performing a similar function such as a Cisco Discovery Protocol (CDP), a Simple Service Discovery Protocol (SSDP), and the like is operated in the same layer or in a layer higher than an IP layer, the LLDP has an advantage of not requiring IP address allocation during a message exchange process for discovery and the like.
FIG. 1 is a diagram illustrating a process in which a service list acquisition apparatus 100, according to the related art, controls each element in order to acquire a service list. As illustrated in FIG. 1, the service list acquisition apparatus 100 includes an application program unit 110, a middleware unit 120, a service discovery module 130, a network layer 140, a data link layer 150, and a physical layer 160. Hereinafter, referring to FIG. 1, a function for each element is described in detail.
When a user of the service list acquisition apparatus 100 intends to use a service such as a game service, a video on demand (VOD) service, and the like, via a wireless network, the user operates the specific application program unit 110 and the application program unit 110 inquires of the middleware unit 120, which performs a communication with the wireless network, whether the wireless network provides the specific service.
The middleware unit 120 checks whether the specific service list exists in the service discovery module 130 existing in the middleware unit 120. When the specific service list exists, the middleware unit 120 performs a communication for using the specific service connecting with the wireless network.
When the specific service list does not exist or a service list with respect to any service which the wireless network provides does not exist as a result of the checking of the middleware unit 120, the service discovery module 130 starts a procedure for acquiring the service list.
The service discovery module 130 accesses an external service list provision apparatus successively controlling the network layer 140, the data link layer 150, and the physical layer 160.
During the above-described process, the physical layer 160 transceives a user's data, which is transmitted via a communication channel, modulating and demodulating the user's data into corresponding signals. Also, the data link layer 150 corrects an error generated during a transmission process in the physical layer 160 and designates a physical address corresponding to a Media Access Control (MAC) address for actually transceiving data with a counterpart. Also, the network layer 140 designates a logical address corresponding to an IP address for transceiving data with a counterpart.
Accordingly, the IP address should be allocated in the network layer 140 so that the service list acquisition apparatus 100 may acquire the service list according to a request of the service discovery module 130.
FIG. 2 is a diagram illustrating a service list acquisition process according to the related art. As illustrated in FIG. 2, the service list acquisition process includes step 230 in which a service list acquisition apparatus 220 receives a beacon signal of a service list provision apparatus 210, step 240 in which the service list acquisition apparatus 220 connects with the service list provision apparatus 210, step 250 in which an IP address is allocated to the service list acquisition apparatus 220, and step 260 in which the service list acquisition apparatus 220 receives a service list which a network provides from the service list provision apparatus 210. Hereinafter, referring to FIG. 2, a function for each step is described in detail.
The service list acquisition apparatus 220 receives a beacon signal, which the service list provision apparatus 210 transmits, in order to check a wireless network coverage area providing a service in step 230. When the beacon signal is not received, attempted service usage is abandoned since the service list acquisition apparatus 220 is out of the wireless network coverage area. When the beacon signal is received, a connection for receiving information from the wireless network that the service list acquisition apparatus 220 exists is attempted in order to use the service from the wireless network in step 240.
An IP address is allocated to the service list acquisition apparatus 220 using a Dynamic Host Configuration Protocol (DHCP) via the service list provision apparatus 210 from the wireless network in step 250. When a communication with the service list provision apparatus 210 is possible using the IP address, the service list is finally transmitted in step 260.
FIG. 3 is a diagram illustrating a network type and a resource change state being exchanged between each element of a network using an LLDP according to the related art.
When each element 310, 320, 330, and 340 configuring a network is connected with the network, network type information such as a port number and the like connected with a device identifier of each element and the network using the LLDP is exchanged between adjacent elements. Each element may identify which element in another network is connected with each element and how the information is exchanged with the element based on the information. Since the network identification information is periodically transmitted to the adjacent element by each element, each element may check for a network change by analyzing type information transmitted from the adjacent element. According to an example in FIG. 3, an IP phone 310 and a switch 330 exchange network type information, e.g. “I'm a switch” and “I'm an IP-Phone”, to each other, and the exchanged information may be stored in a management information storing unit corresponding to a management information base (MIB) and be constantly maintained.
FIG. 4 is a diagram illustrating a structure of an LLDP agent 400 for exchanging actual information between adjacent devices in a conventional LLDP according to the related art. As illustrated in FIG. 4, the LLDP agent 400 includes a device information storing unit 410 corresponding to an LLDP local system MIB, a remote device information storing unit 420 corresponding to an LLDP remote systems MIB, an extended device information storing unit 430 corresponding to an organizationally defined local device LLDP MIB extension, and an extended remote device information storing unit 440 corresponding to an organizationally defined remote device LLDP MIB extensions. Hereinafter, referring to FIG. 4, a function for each element is described in detail.
A port number connected with a device identifier of a corresponding network element, a description with respect to each port, management information, and the like, are stored in the device information storing unit 410. Also, a device identifier with respect to another device connected to the network configuration device via a connected port number, a description with respect to each port, management information, and the like, are stored in the remote device information storing unit 420.
The extended device information storing unit 430 stores physical layer connection information of the corresponding network element, and the like, and the extended remote device information storing unit 440 stores physical layer connection information with respect to another device connected to the network configuration device, and the like.
The LLDP agent 400 manages information stored in the storing units that are controlled by a service discovery module existing in an upper layer of a protocol stack. The LLDP agent also reports the information to the service discovery module transmitting the information to an external apparatus or updates the information transmitted by the external apparatus.
However, the above-described LLDP agent 400 merely transmits a device identifier of a corresponding device and a resource change state to an adjacent device, and may not transmit information of the corresponding device to a long-distance device via the adjacent device and may not be used for service list transmission in a mobile communication environment.
Accordingly, there is a need for an improved new technology for easily exchanging a service list by a convenient procedure between a service list acquisition apparatus, a service list provision apparatus, and a service list forwarding apparatus extending an agent of an LLDP for exchanging system information in a link layer of a conventional wireless network apparatus and using the LLDP.